Process for the production of zinc oxid.



EDOUABD HUNEBELLE, OI PARIS, FRANCE.

r'nocnss m ran rnonocrronor zmc oxm.

Specification of Letters Patent. Application filed ma as, 1914. Serial no. 840,486

No Drawing.

To all whom it may concern:

Be it known that I, EDOUARD HUNnBnmn,

citizen of the French Republic, residing at- Paris, Department ofthe Seine, in France,

have invented certain new and useful Improvements in Processes for the Production of Zinc Oxid; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention has for its object a new or improved process for the conversion into me oxid of. zinc of impure oxids or cardonates of zinc, of cadmia (from iron furnaces) of zinc vapors and of the principal zinkiferous residues from chemical works or factories, by means of magnesia or of carbonate of ma esia aswell as the subseuent recuperatlon of the latter chemical.

he cycle of operation is a closed cycle and merely includes small losses due to the working of the process.

In carrying my invention into practical effect, the material used such as impure oxid of zinc, cadmia from iron Works, zinc vapors, zinc residuum from chemical works, etc., is treated by slightly chlorinated hydrochloric acid. When the action is over, a suitable proportion of sulfate of magnesia is added to the liquor which precipitates as sulfate of lead all traces of chlorid of lead which may have remained in the solution. Carbonate of calcium is subsequently added thereto.

Owing to the action of the chlorinated hydrochloric acid on the material aforesaid, metals and particularly iron are highly 0x1- dized so that the precipitation-by carbonate of calcium of substances capable of being precipitated is complete, and all there is left in the solution 1s. zinc chlorid.

If the substance treated contains neither iron nor metals capable of being precipitated by carbonate of calcium, a small quantity of iron is added thereto the action of which is merely physical and consists in carrying away after precipitation by the carbonate and. in coating the fine and tenuous precipltate the wholesale filtration of which would be diflicult and incomplete.

After filtration, there is obtained an 1nsoluble residuum containing the precipiw tated metals on the one hand and a solution of pure chlorid of zinc on the ot r hand.

The residuum is then treated separately in orderto recuperate the metals therein contalned. The solution of chlorid of zinc is Sub ected to the action of carbonate of magnesia or of magnesia alonea There is formed soluble chlorid of magnesium and insoluble carbonate or oxid of zinc. After filtration and washing pure carbonate or oxid of zinc is obtained. In order to recover the carbonate or oxid of magnesium, I proceed as follows: The zinc having been thoroughly precipitated either by the aid of heat or without, solutions of chlorid of magnesium are obtained and do not register much more than 30 B. at an ordinary temperature. These solutions are concentrated by the lost heat derived from the furnaces or ovens so as to obtain the following salt: MgCl '-|6Aq. This salt is introduced into a suitable oven and gradu-' ally heated. At a temperature of 165, this salt is decomposed into HCl and MgO and this decomposition progresses up to 250. From this moment steam is injected into the mixture which contains a strong proportion of oxychlorid or the said mixture may be otherwise hydrated. The temperature is Patented Oct. 17, 1916.

gradually raised to from 550 to 600. There is then evolved under the action of air and steam which however must be suitably regulated a mixture of chlorin and hydrochloric acid which are condensed together in suitable condensing apparatus. The whole of the acid collected which may be called chlorinated hydrochloric acid will serve for a fresh treatment of zinkiferous material. The residuum from this calcination of chlorid of magnesium is pure magnesia which may be readily converted into carbonate and will serve for the precipitation of zinc as hereinbefore stated. In short it will be seen that this process forms a complete cycle without any loss of chemicals except incidental losses in the Working.

I claim:

1. The method of obtaining pure zinc compounds from. zinkiferous materials which consists in treating the zinkiferous material wth hydrochloric acid, and then Q 7 1,201 ,eec

adding calcium carbonate to precipitate imbonate to precipitate impurities and. leave purities and to leave substantially pure zinc substantially pure zinc chloricl. chlorid. In testimony whereof I afix my signa- '2 The method of obtaining pure zinc ture, in presenceof two Witnesses.

5 compounds from zinkiferous materials, I EDOUARD HUNEBELLE.

which consists in treatin the zinkiferous Witnesses: material with hydrochloric acid, and then CHAS. P. PREs'sLY, adding magnesium sulfate and calcium car- LOUIS Fossn. 

